It is known in retail outlets to vary the number of checkouts open according to the number of people queuing. This is normally achieved in two ways; the first is by long-term scheduling, typically done weeks in advance. This provides a fixed schedule for the retailer to work to. On the day, a manager may react to the queues that form, by taking staff from some other duties to open extra checkouts. However, this requires the manager to be able to react to the number of people queuing at any instant. It is desirable to provide a computer system which can predict the number of facilities (checkouts) needed ahead of time.
Some supermarkets guarantee maximum queue lengths and use this as a marketing tool. In these cases, there is a target queue length N. Therefore, if the total number queuing is Q, the number of checkouts required is Q/N. However, in order to have the required number of checkouts open in order to keep the queues shorter than the target length, the supermarket operator needs to be able to measure and react to the number of people queuing. Even where stores do not guarantee a maximum queue length, it should be noted that, in general, stores implicitly make a judgement about how long queues should be, and therefore a queue management system has general applicability.
It should also be noted that the number of people queuing may be considered and measured in shopping units, where a shopping unit is a number of people associated with one transaction, trolley or basket, and this is another factor to be considered when attempting to measure and control queues.
There have been some past efforts to provide a computer system for predicting the required number of facilities (e.g. checkouts) ahead of time.
U.S. Pat. No. 3,808,410 employs a system which translates door arrival information directly into a checkout requirement via a pre-determined lookup table.
U.S. Pat. No. 5,557,513 uses a predetermined statistical model of store transit time, combined with door arrival information, to predict checkout requirement.